11.1.3 You need to know the install year

The install year directly determines the system's value.

For example, California systems installed before 2023 export at 1:1 retail credit — which is very valuable.

But that pricing arrangement is only valid for 20 years, starting from the date of grid interconnection.

When the 20 years run out, regardless of system size, a battery-less system drops to less than 1/4 of its prior value.

So if the seller's system is approaching the 20-year cliff, you should not pay any premium for it. In fact, you can argue the opposite: "this system is about to lose most of its value, and the cost to remove and upgrade it is non-trivial. Lower your asking price."